Secondary battery

ABSTRACT

Various embodiments of the present invention relate to a secondary battery. The technical problem to be solved is to provide the secondary battery which can improve the insulation strength of first and second multi-tabs, by forming the first and second multi-tabs of first and second electrode assemblies symmetrically with respect to each other, and also can improve the insulation strength of the first and second multi-tabs by forming an insulating layer on the first and second multi-tabs of the first and second electrode assemblies. To this end, disclosed is a secondary battery comprising a case; a first electrode assembly which is housed inside of the case and has a first multi-tab; a second assembly which is housed side by side with the first electrode assembly on the inside of the case and has a second multi-tab; and a cap plate which blocks the case and has an electrode terminal electrically connected to the first and second multi-tabs of the first and second electrode assemblies, wherein the first and second multi-tabs are formed symmetrically to each other with respect to a mutual boundary region of the first and second electrode assemblies, and an insulating layer is coated on the surface of the first and second multi-tabs.

TECHNICAL FIELD

Various embodiments of the present invention relate to a secondarybattery.

BACKGROUND ART

A secondary battery is a power storage system which can provide anexcellent energy density for converting electrical energy into chemicalenergy and storing the same. Unlike primary batteries, which cannot berecharged, secondary batteries are rechargeable and are widely used inIT devices, such as smart phones, cellular phones, notebook computers,tablet PCs, or the like. Recently, in order to prevent environmentalpollution, electric vehicles have attracted high attention andhigh-capacity secondary batteries are employed to the electric vehicles.Accordingly, the development of secondary batteries having advantageouscharacteristics including high energy density, high power output andstability, is required.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the describedtechnology and therefore it may contain information that does not formthe prior art that is already known in this country to a person ofordinary skill in the art.

Technical Problems to be Solved

Various embodiments of the present invention provide a secondarybattery.

In an example, various embodiments of the present invention provide asecondary battery which can improve the insulation strength of first andsecond multi-tabs, by forming the first and second multi-tabs of firstand second electrode assemblies symmetrically with respect to eachother.

In another example, various embodiments of the present invention providea secondary battery which can improve the insulation strength ofmulti-tabs by forming an insulating layer on the multi-tabs of electrodeassemblies.

Technical Solutions

In accordance with an aspect of the present invention, the above andother objects can be accomplished by providing a secondary batteryincluding a case; a first electrode assembly housed inside of the caseand having a first multi-tab; a second electrode assembly housed insideof the case side by side with the first electrode assembly and having asecond multi-tab; and a cap plate closing the case and having electrodeterminals electrically connected to the first and second multi-tabs ofthe first and second electrode assemblies, wherein the first and secondmulti-tabs are formed to be symmetrical to each other with respect to amutual boundary region of the first and second electrode assemblies, andan insulating layer is coated on the surfaces of the first and secondmulti-tabs.

The first and second multi-tabs may be located only at regions closer tothe case than to the mutual boundary region of the first and secondelectrode assemblies, respectively.

The first and second multi-tabs may be extended to the electrodeterminals from regions closer to the case than to the mutual boundaryregion of the first and second electrode assemblies, respectively. Thefirst and second multi-tabs may include first regions extended from thefirst and second electrode assemblies, second regions extended from thefirst regions and located adjacent to the case, and third regions bentfrom the second regions and connected to the electrode terminals,respectively.

The first electrode assembly may include a first winding center, thesecond electrode assembly may include a second winding center, the casemay include a first long side portion closely contacting the firstelectrode assembly, a second long side portion closely contacting thesecond electrode assembly, the first multi-tab may be positioned betweenthe first winding center and the first long side portion, and the secondmulti-tab may be positioned between the second winding center and thesecond long side portion.

The first and second multi-tabs may be located only at regions closer tothe mutual boundary region than to the case.

The first and second multi-tabs may be extended to the electrodeterminals from regions closer to the mutual boundary region than to thecase. The first and second multi-tabs may include first regions extendedfrom the first and second electrode assemblies, second regions extendedfrom the first regions and located adjacent to the case, and thirdregions bent from the second regions and connected to the electrodeterminals, respectively.

The first electrode assembly may include a first winding center, thesecond electrode assembly may include a second winding center, the firstmulti-tab may be positioned between the first winding center and themutual boundary region, and the second multi-tab may be positionedbetween the second winding center and the mutual boundary region.

The first and second multi-tabs may include outer multi-tabs located inregions closer to the case than to the mutual boundary region, and innermulti-tabs located in regions closer to the mutual boundary region thanto the case, respectively.

The insulating layer may include an insulating organic material.

The insulating layer may include an insulating inorganic material.

The insulating layer may include an inorganic filler and an organicbinder.

Each of the first and second electrode assemblies may include a firstelectrode plate including a first current collector plate and a firstelectrically active material layer coated on the first current collectorplate; a separator positioned at one side of the first electrode plate;and a second electrode plate include a second current collector plateand a second electrically active material layer coated on the secondcurrent collector plate, wherein the first multi-tab is formed such thatthe first current collector plate is extended to the outside of thefirst electrically active material layer of the first electrode plate ofthe first electrode assembly, and the second multi-tab is formed suchthat the second current collector plate is extended to the outside ofthe second electrically active material layer of the second electrodeplate of the second electrode assembly.

The insulating layer and the separator may be positioned between each ofthe first and second multi-tabs and the second electrode plate.

The secondary battery may further include a safety function layer (SFL)located on the second electrically active material layer. Here, theinsulating layer, the separator and the SFL may be positioned betweeneach of the first and second multi-tabs and the second electrode plate.

Advantageous Effects

As described above, according to various embodiments of the presentinvention, a secondary battery is provided, which can increase theinsulation level of first and second multi-tabs by forming the first andsecond multi-tabs of first and second electrode assemblies to besymmetrical to each other.

For example, according to an embodiment of the present invention, thefirst and second multi-tabs of the first and second electrode assembliesare extended and bent to be symmetrical with each other from regionslocated adjacent to the case to electrode terminals with respect toelectrode terminals or the boundary region (or the contact area) of thefirst and second electrode assemblies, thereby preventing the first andsecond multi-tabs and regions (e.g., the case, the cap plate and/orpredetermined regions of the first and second electrode assemblies)having polarities opposite to the first and second multi-tabs from beingelectrically short-circuited to each other in the first and secondelectrode assemblies.

For another example, according to an embodiment of the presentinvention, the first and second multi-tabs of the first and secondelectrode assemblies are extended and bent to be symmetrical with eachother from regions located adjacent to the boundary region (or thecontact area) of the first and second electrode assemblies to electrodeterminals with respect to the electrode terminals or the boundary region(or the contact area) of the first and second electrode assemblies,thereby preventing the first and second multi-tabs and regions (e.g.,the case, the cap plate and/or predetermined regions of the first andsecond electrode assemblies) having polarities opposite to the first andsecond multi-tabs from being electrically short-circuited to each otherin the first and second electrode assemblies.

For still another example, according to an embodiment of the presentinvention, the first and second multi-tabs located at first sides of thefirst and second electrode assemblies are extended and bent to besymmetrical with each other from regions located adjacent to the case tothe boundary region (or the contact area) of electrode terminals or thefirst and second electrode assemblies to electrode terminals, and thefirst and second multi-tabs located at second sides of the first andsecond electrode assemblies are extended and bent to be symmetrical witheach other from regions located adjacent to the boundary region of thefirst and second electrode assemblies to the electrode terminals,thereby improving coupling reliability between the first and secondelectrode assemblies and the electrode terminals and preventing thefirst and second multi-tabs and the regions (e.g., the case, the capplate and/or predetermined regions of the first and second electrodeassemblies) having polarities opposite to the first and secondmulti-tabs from being electrically short-circuited to each other.

In addition, an embodiment of the present invention provides a secondarybattery capable of increasing the insulation level of multi-tabs byforming an insulating layer on the multi-tabs of an electrode assembly.

For example, according to an embodiment of the present invention, aninsulating layer made of an organic material, an inorganic material,and/or an organic-inorganic composite material, is located on one orboth surfaces of a positive multi-tab of an electrode assembly, therebyproviding a triple insulating structure including the insulating layerbetween the positive multi-tab and a negative electrode plate, aseparator and/or a safety function layer (SFL) (i.e., a ceramic layercoated on a surface of an negative electrode active material layer).Accordingly, even if the positive multi-tab is bent in various types tobe connected to an electrode terminal, an electrical short circuitbetween the positive multi-tab and the negative electrode plate can besuppressed. That is to say, the insulation level of the positivemulti-tab can be increased.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A, 1B and 1C are a perspective view, a cross-sectional view andan exploded perspective view of a secondary battery according to anembodiment of the present invention.

FIGS. 2A and 2B are a plan view and a partially cross-sectional view offirst and second electrode assemblies in the secondary battery accordingto an embodiment of the present invention.

FIGS. 3A and 3B are a plan view and a partially cross-sectional view offirst and second electrode assemblies in a secondary battery accordingto another embodiment of the present invention.

FIGS. 4A and 4B are a plan view and a partially cross-sectional view offirst and second electrode assemblies in a secondary battery accordingto another embodiment of the present invention.

FIGS. 5A and 5B are enlarged cross-sectional views illustrating statesbefore and after bending multi-tabs according to an embodiment of thepresent invention.

FIGS. 6A and 6B are enlarged cross-sectional views illustrating statesbefore and after bending multi-tabs according to another embodiment ofthe present invention.

FIGS. 7A and 7B are enlarged cross-sectional views of multi-tabsaccording to another embodiment of the present invention.

FIGS. 8A to 8C are schematic views illustrating a manufacturing methodof a secondary battery according to an embodiment of the presentinvention.

FIG. 9 is a perspective view illustrating an example of a battery moduleusing a secondary battery according to an embodiment of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of the present invention will bedescribed in detail.

Various embodiments of the present invention may be embodied in manydifferent forms and should not be construed as being limited to theexample embodiments set forth herein. Rather, these example embodimentsof the disclosure are provided so that this disclosure will be thoroughand complete and will convey inventive concepts of the disclosure tothose skilled in the art.

In the accompanying drawings, sizes or thicknesses of various componentsare exaggerated for brevity and clarity. Like numbers refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items. Inaddition, it will be understood that when an element A is referred to asbeing “connected to” an element B, the element A can be directlyconnected to the element B or an intervening element C may be presentand the element A and the element B are indirectly connected to eachother.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprise or include” and/or“comprising or including,” when used in this specification, specify thepresence of stated features, numbers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, numbers, steps, operations, elements,components, and/or groups thereof.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various members, elements, regions, layersand/or sections, these members, elements, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one member, element, region, layer and/or section fromanother. Thus, for example, a first member, a first element, a firstregion, a first layer and/or a first section discussed below could betermed a second member, a second element, a second region, a secondlayer and/or a second section without departing from the teachings ofthe present disclosure.

Spatially relative terms, such as “below,” “beneath,” “lower,” “above,”“upper,” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “on” or “above” the otherelements or features. Thus, the exemplary term “below” can encompassboth an orientation of above and below.

In addition, as used herein, the term “separator” includes a separatorgenerally used in liquid electrolyte batteries using a liquidelectrolyte having a low affinity to the separator. Further, as usedherein, the term “separator” may include an intrinsic solid polymerelectrolyte in which the electrolyte is strongly bound to the separatorto then be recognized as being the same as the separator, and/or a gelsolid polymer. Therefore, the meaning of the separator should be definedas specifically defined in the specification of the present disclosure.

Referring to FIGS. 1A, 1B and 1C, a perspective view, a cross-sectionalview and an exploded perspective view of a secondary battery accordingto an embodiment of the present invention are illustrated.

As illustrated in FIGS. 1A, 1B and 1C, the secondary battery 100according to an embodiment of the present invention may include a case110, first and second electrode assemblies 120A and 120B, a cap plate130, a first electrode terminal 140 and a second electrode terminal 150.

The case 110 may be made of a conductive metal, such as aluminum, analuminum alloy or nickel plated steel, and may be substantially shapedof a hexahedron having an opening through which the electrode assemblies120A and 120B can be inserted into the case 110. While the opening isnot shown in FIG. 1B because the case 110 and the cap plate 130 areassembled with each other, it may be a substantially opened part of atop portion of the case 110. Meanwhile, since the internal surface ofthe case 110 is insulated, the case 110 may be insulated from the firstand second electrode assemblies 120A and 120B. Here, the case 110 mayalso referred to as a can in some instances.

The case 110 may include a first long side portion 111 having arelatively large area, a second long side portion 112 facing the firstlong side portion 111 and having a relatively large area, a first shortside portion 113 connecting first ends of the first and second long sideportions 111 and 112 and having a relatively small area, a second shortside portion 114 facing the third short side portion 113, connectingsecond ends of the first and second long side portions 111 and 112 andhaving a relatively small area, and a bottom portion 115 connecting thefirst and second long side portions 111 and 112 and the first and secondshort side portions 113 and 114.

The first electrode assembly 120A is assembled inside of the case 110.Particularly, one surface of the first electrode assembly 120A iscoupled to the case 110 in a state in which it is tightly adheredto/brought into contact with the first long side portion 111 of the case110. The first electrode assembly 120A may be manufactured by winding orlaminating a stacked structure including a first electrode plate 121, aseparator 122, and a second electrode plate 123, which are thin platesor layers. Here, the first electrode plate 121 may operate as a positiveelectrode and the second electrode plate 123 may operate as a negativeelectrode. Of course, polarities of the first electrode plate 121 andthe second electrode plate 123 may be reversed. In addition, if thefirst electrode assembly 120A is manufactured in a winding type, a firstwinding center 125A (or a first winding leading edge) where winding isstarted may be located at the center of the first electrode assembly120A.

The first electrode plate 121 may include a first current collectorplate 121 a made of a metal foil or mesh including aluminum or analuminum alloy, a first coating portion 121 b having a firstelectrically active material, such as a transition metal oxide, on thefirst current collector plate 121 a, a first non-coating portion (or afirst uncoated portion) 121 c on which the first electrically activematerial is not coated, and a first electrode first multi-tab 161outwardly (or upwardly) extended from the first non-coating portion 121c and electrically connected to the first electrode terminal 140. Here,the first electrode first multi-tab 161 may become a passageway of theflow of current between the first electrode plate 121 and the firstelectrode terminal 140 and may include multiple first electrode firsttabs arranged in a stacked type to be referred to as multi-tabs. Inaddition, the first electrode first multi-tab 161 may be provided suchthat the first non-coating portion 121 c is upwardly extended/protruded.Here, the first electrode may be a positive electrode.

The second electrode plate 123 may include a second current collectorplate 123 a made of a metal foil or mesh including copper, a copperalloy, nickel or a nickel alloy, a second coating portion 123 b having asecond electrically active material, such as graphite or carbon, on thesecond current collector plate 123 a, a second non-coating portion (or asecond uncoated portion) 123 c on which the second electrically activematerial is not coated, and a second electrode first multi-tab 171outwardly (or upwardly) extended from the second non-coating portion 123c and electrically connected to the second electrode terminal 150. Here,the second electrode first multi-tab 171 may become a passageway of theflow of current between the second electrode plate 123 and the secondelectrode terminal 150 and may include multiple second electrode firsttabs arranged in a stacked type to be referred to as multi-tabs. Inaddition, the second electrode first multi-tab 171 may be provided suchthat the second non-coating portion 123 c is upwardlyextended/protruded. Here, the second electrode may be a negativeelectrode.

The separator 122 may be positioned between the first electrode plate121 and the second electrode plate 123 to prevent an electrical shortcircuit from occurring between the first electrode plate 121 and thesecond electrode plate 123 and to allow movement of lithium ions. Theseparator 122 may include polyethylene, polypropylene or a compositefilm of polyethylene and polypropylene. However, the material of theseparator 122 is not limited to the specific materials listed herein. Inaddition, if an inorganic solid electrolyte is used, the separator 122may not be provided.

The second electrode assembly 120B may have substantially the samestructure, type and/or material as those of the first electrode assembly120A. Therefore, detailed descriptions of the second electrode assembly120B will be omitted. However, one surface of the second electrodeassembly 120B is coupled to the case 110 in a state in which it istightly adhered to/brought into contact with the second long sideportion 112 of the case 110. In addition, if the second electrodeassembly 120B is manufactured in a winding type, a second winding center125B (or a second winding leading edge) where winding is started may belocated at the center of the second electrode assembly 120B.

In addition, the first and second electrode assemblies 120A and 120Binclude a mutual boundary region where the first and second electrodeassemblies 120A and 120B face each other inside of the case 110 or acontact area 190 where the first and second electrode assemblies 120Aand 120B are tightly adhered to/brought into contact with each other.That is to say, the first and second electrode assemblies 120A and 120Bmay be assembled inside of the case 110 in a state in which they aretightly adhered to/brought into contact with each other.

Meanwhile, the second electrode assembly 120B may include a firstelectrode second multi-tab 162 outwardly (or upwardly) extended from thefirst electrode plate 121 and electrically connected to the firstelectrode terminal 140. Here, the first electrode second multi-tab 162may become a passageway of the flow of current between the firstelectrode plate 121 and the first electrode terminal 140 and may includemultiple first electrode second tabs arranged in a stacked type to bereferred to as multi-tabs. In addition, the first electrode secondmulti-tab 162 may be provided such that the first non-coating portion121 c is upwardly extended/protruded.

In addition, the second electrode assembly 120B may include a secondelectrode second multi-tab 172 outwardly (or upwardly) extended from thesecond electrode plate 123 and electrically connected to the secondelectrode terminal 150. Here, the second electrode second multi-tab 172may become a passageway of the flow of current between the secondelectrode plate 123 and the second electrode terminal 150 and mayinclude multiple second electrode second tabs arranged in a stacked typeto be referred to as multi-tabs. In addition, the second electrodesecond multi-tab 172 may be provided such that the second non-coatingportion 123 c is upwardly extended/protruded.

Meanwhile, an axis of each of the first and second winding centers 125Aand 125B of the first and second electrode assemblies 120A and 120B,that is, a winding axis, is substantially parallel or horizontal to aterminal axis of each of the first and second electrode terminals 140and 150. Here, the winding axis and the terminal axis may mean anup-and-down axis in FIGS. 1B and 1C, and the expression “the windingaxis and the terminal axis being substantially parallel or horizontal toeach other” may mean that the winding axis and the terminal axis may notmeet each other even if the winding axis and the terminal axis areextended or may meet each other when the winding axis and the terminalaxis are extraordinarily extended.

In addition, as described above, the first and second multi-tabs 161 and162 extended and bent a predetermined length are positioned between thefirst and second electrode assemblies 120A and 120B and the firstelectrode terminal 140, and the first and second multi-tabs 171 and 172extended and bent a predetermined length are positioned between thefirst and second electrode assemblies 120A and 120B and the secondelectrode terminal 150. That is to say, the first and second multi-tabs161 and 162 located at first sides may be extended and bent from topends of the first and second electrode assemblies 120A and 120B towardthe first electrode terminal 140 so as to be substantially symmetricalwith each other to then be connected or welded to the first electrodeterminal 140. In addition, the first and second multi-tabs 171 and 172located at second sides may also be extended and bent from the top endsof the first and second electrode assemblies 120A and 120B toward thesecond electrode terminal 150 so as to be substantially symmetrical witheach other to then be connected or welded to the second electrodeterminal 150.

Substantially, each of the first and second multi-tabs 161 and 162located at one side may be the first non-coating portion 121 c itself,which is a region of the first electrode plate 121, without a firstactive material coated thereon, or may be a separate member connected tothe first non-coating portion 121 c. Here, the separate member may bemade of one selected from the group consisting of aluminum, an aluminumalloy, nickel, a nickel alloy, copper, a copper alloy, and equivalentsthereof.

In addition, each of the first and second multi-tabs 171 and 172 locatedat the other side may be the second non-coating portion 123 c itself,which is a region of the second electrode plate 123, without a secondactive material coated thereon, or may be a separate member connected tothe second non-coating portion 123 c. Here, the separate member may bemade of one selected from the group consisting of nickel, a nickelalloy, copper, a copper alloy, aluminum, an aluminum alloy, andequivalents thereof.

As described above, since the first and second winding axes of the firstand second electrode assemblies 120A and 120B and the terminal axes ofthe first and second electrode terminals 140 and 150 are substantiallyparallel or horizontal to each other, an electrolyte injection directionand the winding axes are also substantially parallel or horizontal toeach other. Therefore, the first and second electrode assemblies 120Aand 120B exhibit high electrolyte impregnation capability when anelectrolyte is injected and internal gases are rapidly transferred to asafety vent 136 during over-charge, enabling the safety vent 136 toquickly operate.

In addition, the first and second multi-tabs 161/171 and 162/172 (oruncoated portions or separate members) of the first and second electrodeassemblies 120A and 120B are extended and bent to be are directlyelectrically connected to the first and second electrode terminals 140and 150, which shortens electrical paths, thereby reducing internalresistance of the secondary battery 100 while reducing the number ofcomponents of the secondary battery 100.

In particular, since the first and second multi-tabs 161/171 and 162/172(or uncoated portions or separate members) of the first and secondelectrode assemblies 120A and 120B are directly electrically connectedto first and second electrode terminals 140 and 150 while beingsymmetrical with each other, unnecessary electrical short circuitsbetween the first and second multi-tabs 161/171 and 162/172 and regions(e.g., the case, cap plate and/or predetermined portions of the firstand second electrode assemblies 120A and 120B) having polaritiesopposite to the first and second multi-tabs 161/171 or 162/172 can beprevented. In other words, insulation levels of the first and secondmulti-tabs 161/171 and 162/172 can be improved by the symmetricalstructures of the first and second multi-tabs 161/171 and 162/172.

The first and second electrode assemblies 120A and 120B may be housed inthe case 110 together with an electrolyte. The electrolyte may includean organic solvent, such as ethylene carbonate (EC), propylene carbonate(PC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), or dimethylcarbonate (DMC), and a lithium salt such as LiPF₆or LiBF₄. In addition,the electrolyte may be in a liquid, sold or gel phase.

The cap plate 130 may be substantially shaped of a rectangle havinglengths and widths and may be coupled to the case 110. That is to say,the cap plate 130 may seal an opening of the case 110 and may be made ofthe same material as the case 110. For example, the cap plate 130 may becoupled to the case 110 by laser and/or ultrasonic welding. Here, thecap plate 130 may also be referred to as a cap assembly in someinstances.

The cap plate 130 may include a plug 134 closing an electrolyteinjection hole, and a safety vent 136 clogging a vent hole. In addition,the safety vent 136 may include a notch configured to be easily openedat a preset pressure.

The first electrode terminal 140 may include a first electrode terminalplate 141 positioned on a top surface of the cap plate 130, a firstupper insulation plate 142 positioned between the first electrodeterminal plate 141 and the cap plate 130, a first lower insulation plate143 positioned on a bottom surface of the cap plate 130, a first currentcollector plate 144 positioned on a bottom surface of the first lowerinsulation plate 143, and a first electrode terminal pillar 145electrically connecting the first electrode terminal plate 141 and thefirst current collector plate 144. In addition, the secondary battery100 according to an embodiment of the present invention may furtherinclude a first seal insulation gasket 146 insulating the cap plate 130and the first electrode terminal pillar 145 from each other.

Here, the first and second multi-tabs 161 and 162 of the first andsecond electrode assemblies 120A and 120B may be electrically connectedto the first current collector plate 144 of the first electrode terminal140 so as to be symmetrical with each other.

The second electrode terminal 150 may include a second electrodeterminal plate 151 positioned on the top surface of the cap plate 130, asecond upper insulation plate 152 positioned between the secondelectrode terminal plate 151 and the cap plate 130, a second lowerinsulation plate 153 positioned on the bottom surface of the cap plate130, a second current collector plate 154 positioned on a bottom surfaceof the second lower insulation plate 153, and a second electrodeterminal pillar 145 electrically connecting the second electrodeterminal plate 151 and the second current collector plate 154. Inaddition, the secondary battery 100 according to an embodiment of thepresent invention may further include a second seal insulation gasket156 insulating the cap plate 130 and the second electrode terminalpillar 155 from each other.

Here, the first and second multi-tabs 171 and 172 of the first andsecond electrode assemblies 120A and 120B may be electrically connectedto the second current collector plate 154 of the second electrodeterminal 150 so as to be symmetrical with each other.

Meanwhile, in an embodiment of the present invention, an insulationplate 180 is further positioned between each of the first and secondelectrode assemblies 120A and 120B, the first and second multi-tabs161/171 and 162/172 and the first and second electrode terminals 140 and150, thereby preventing the first and second multi-tabs 161/171 or162/172 and regions (e.g., the case, the cap plate and/or thepredetermined regions of the first and second electrode assemblies)having polarities opposite to the first and second multi-tabs 161/171 or162/172 from being electrically short-circuited to each other. Theinsulation plate 180 may be made of, for example, but not limited to, asuper engineering plastic, such as polyphenylene sulfide (PPS), havingexcellent dimension stability and maintaining a high strength andstiffness up to approximately 220° C.

As described above, in the secondary battery 100 according to theembodiment of the present invention, the first and second multi-tabs161/171 and 162/172 of the first and second electrode assemblies 120Aand 120B are configured such that they are extended and bent to besymmetrical with each other with respect to the first and secondelectrode terminals 140 and 150 or the mutual boundary region (orcontact area) 190 of the first and second electrode assemblies 120A and120B), thereby preventing the first and second multi-tabs 161/171 or162/172 and the regions (e.g., the case 110, the cap plate 130 and/orthe predetermined regions of the first and second electrode assemblies120A and 120B) having polarities opposite to the first and secondmulti-tabs 161/171 or 162/172 from being electrically short-circuited toeach other.

That is to say, if the first and second multi-tabs 161/171 and 162/172are configured to be asymmetrical with each other with respect to thefirst and second electrode terminals 140 and 150 or the mutual boundaryregion 190 of the first and second electrode assemblies 120A and 120B),a probability of electrical short circuits occurring between the firstand second multi-tabs 161/171 and 162/172 and the case 110, the capplate 130 and/or the predetermined regions of the first and secondelectrode assemblies 120A and 120B having polarities opposite to thefirst and second multi-tabs 161/171 or 162/172, may be increased.However, like in the embodiment of the present invention, if the firstand second multi-tabs 161 and 162 are configured to be symmetrical witheach other, the probability of occurrence of such electrical shortcircuits can be reduced.

For example, a probability of electrical short circuits occurringbetween the positive electrode first and second multi-tabs 161 and 162configured to be symmetrical with each other and the negative electrodenon-coating portions 123 c of the first and second electrode assemblies120A and 120B, is smaller than a probability of electrical shortcircuits occurring between positive electrode first and secondmulti-tabs configured to be asymmetrical with each other and negativeelectrode non-coating portions of first and second electrode assemblies,but aspects of the present invention are not limited thereto. Inaddition, for example, a probability of electrical short circuitsoccurring between the negative electrode first and second multi-tabs 171and 172 configured to be symmetrical with each other and the positiveelectrode non-coating portions 121 c of the first and second electrodeassemblies 120A and 120B, is smaller than a probability of electricalshort circuits occurring between negative electrode first and secondmulti-tabs configured to be asymmetrical with each other and positiveelectrode non-coating portions of first and second electrode assemblies,but aspects of the present invention are not limited thereto.

In other words, if the first and second multi-tabs 161/171 and 162/172of the first and second electrode assemblies 120A and 120B areconfigured to be symmetrical with each other, the number or area ofmanagement regions for preventing electrical short circuits between thefirst and second multi-tabs 161/171 or 162/172 and the regions havingopposite polarities, that is, the case 110, the cap plate 130 and/or thepredetermined regions of the first and second electrode assemblies 120Aand 120B, may be reduced. Accordingly, it is easy to prevent theelectrical short circuits between the first and second multi-tabs161/171 and 162/172 and the regions having the opposite polarities.However, if the first and second multi-tabs 161/171 and 162/172 of thefirst and second electrode assemblies 120A and 120B are configured to beasymmetrical with each other, the number or area of management regionsfor preventing electrical short circuits between the first and secondmulti-tabs 161/171 or 162/172 and the regions having oppositepolarities, may be increased. Accordingly, it is difficult to preventthe electrical short circuits between the first and second multi-tabs161/171 and 162/172 and the regions having the opposite polarities.

Referring to FIGS. 2A and 2B, a plan view and a partiallycross-sectional view of first and second electrode assemblies in thesecondary battery according to an embodiment of the present inventionare illustrated.

As illustrated in FIGS. 2A and 2B, the first electrode assembly 120A mayinclude a first winding center 125A (or a first winding leading edge)where winding is started, and the second electrode assembly 120B mayalso include a second winding center 125B (or a second winding leadingedge) where winding is started. In addition, the first and secondelectrode assemblies 120A and 120B may have a mutual boundary region (orcontact area) 190) therebetween.

In the following description, outer regions of the first and secondelectrode assemblies 120A and 120B may mean regions spaced apart fromthe mutual boundary region 190 of the first and second electrodeassemblies 120A and 120B and closer to the first and second long sideportions 111 or 112 of the case 110, and inner regions of the first andsecond electrode assemblies 120A and 120B may mean regions spaced apartfrom the first and second long side portions 111 or 112 of the case 110and closer to the mutual boundary region 190 of the first and secondelectrode assemblies 120A and 120B. In addition, in the followingdescription, the outer regions of the first and second electrodeassemblies 120A and 120B may mean regions from the first and secondwinding centers 125A or 125B to the first and second long side portions111 or 112 of the case 110, and the inner regions of the first andsecond electrode assemblies 120A and 120B may mean regions from thefirst and second winding centers 125A or 125B to the mutual boundaryregion 190 of the first and second electrode assemblies 120A and 120B.It should be understood that definitions of the outer and inner regionsof the first and second electrode assemblies 120A and 120B can becommonly applied to all embodiments of the present invention.

As illustrated in FIG. 2A, the first and second electrode assemblies120A and 120B may include the first and second multi-tabs 161/162 or171/172 located at their outer regions so as to be symmetrical with eachother with respect to the mutual boundary region 190. The firstmulti-tabs 161 and 171 may be located only at, for example, but notlimited to, the outer region of the first electrode assembly 120A. Thatis to say, the first multi-tabs 161 and 171 may not be located at theinner regions of the first electrode assembly 120A. In addition, thesecond multi-tabs 162 and 172 may also be located only at the outerregions of the second electrode assembly 120B. That is to say, thesecond multi-tabs 162 and 172 may not be located at the inner regions ofthe second electrode assembly 120B. More specifically, as illustrated inFIG. 2A, the first multi-tabs 161 and 171 may be located only at roughlyupper regions of the first winding center 125A in the first electrodeassembly 120A (i.e., regions located adjacent to the first long sideportion 111 of the case 110), and the second multi-tabs 162 and 172 maybe located only at roughly lower regions of the second winding center125B in the second electrode assembly 120B (i.e., regions locatedadjacent to the second long side portion 112 of the case 110).Therefore, the maximum distance between the first and second multi-tabs161/162 or 171/172 may be equal to or slightly smaller than the maximumoverall width (or thickness) of the first and second electrodeassemblies 120A and 120B.

In addition, as illustrated in FIG. 2B, the first and second electrodeassemblies 120A and 120B may include the first and second multi-tabs 161and 162 extended and bent from the outer regions so as to be symmetricalwith each other with respect to the mutual boundary region 190 or theelectrode terminal 140. The first and second multi-tabs 161 and 162 maybe extended and bent from, for example, but not limited to, the outerregions of the first and second electrode assemblies 120A and 120B tothe electrode terminal 140 so as to be symmetrical with each other withrespect to the mutual boundary region 190. In other words, the first andsecond multi-tabs 161 and 162 may be extended and bent to the electrodeterminal 140 from regions closer to the case 110 (i.e., the first longside portion or the second long side portion) than to the mutualboundary region 190 of the first and second electrode assemblies 120Aand 120B, respectively.

Still in other words, the first and second multi-tabs 161 and 162 mayinclude first regions 161 a and 162 a extended from the outer regions ofthe first and second electrode assemblies 120A and 120B, second regions161 b and 162 b extended from the first regions 161 a and 162 a to beadjacent to the case 110, and third regions 161 c and 162 c bent fromthe second regions 161 b and 162 b to be electrically connected to theelectrode terminal 140, respectively.

Here, as the first regions 161 a and 162 a get closer from the case 110(i.e., the first long side portion or the second long side portion) tothe mutual boundary region 190 of the first and second electrodeassemblies 120A and 120B, bending angles of the first regions 161 a and162 a are more increased. In addition, the second regions 161 b and 162b may be substantially parallel with a longitudinal direction of thecase 110 (i.e., the first long side portion or the second long sideportion). In addition, the third regions 161 c and 162 c may beconnected to the electrode terminal 140 while being bent roughly atright angle from the second regions 161 b and 162 b.

In addition, since the insulation plate 180 is further located of thefirst and second electrode assemblies 120A and 120B and the first andsecond multi-tabs 161 and 162, and the electrode terminal 140,electrical short circuits may not occur between the case, the cap plateand/or the predetermined regions of the first and second electrodeassemblies 120A and 120B, which have polarities opposite to the firstand second multi-tabs 161 and 162. In particular, the insulation plate180 is placed roughly on the separator 122 of each of the first andsecond electrode assemblies 120A and 120B.

As described above, according to the embodiment of the presentinvention, the first and second multi-tabs 161 and 162 are extended andbent from the outer regions of the first and second electrode assemblies120A and 120B to the electrode terminal 140 so as to be symmetrical witheach other with respect to the electrode terminal 140 or the mutualboundary region 190 of the first and second electrode assemblies 120Aand 120B, thereby suppressing electrical short circuits between thefirst and second multi-tabs 161 and 162 and the regions havingpolarities opposite thereto, for example, the case, the cap plate and/orthe predetermined regions of the first and second electrode assemblies.

Referring to FIGS. 3A and 3B, a plan view and a partiallycross-sectional view of first and second electrode assemblies in asecondary battery according to another embodiment of the presentinvention are illustrated.

As illustrated in FIG. 3A, the first and second electrode assemblies120A and 120B may include first and second multi-tabs 261/262 or 271/272located at their inner regions so as to be symmetrical with each otherwith respect to the mutual boundary region 190 of the first and secondelectrode assemblies 120A and 120B. The first multi-tabs 261 and 271 maybe located only at, for example, but not limited to, the inner regionsof the first electrode assembly 120A. That is to say, the firstmulti-tabs 261 and 271 may not be located at the outer regions of thefirst electrode assembly 120A. In addition, the second multi-tabs 262and 272 may also be located only at the inner regions of the secondelectrode assembly 120B. That is to say, the second multi-tabs 262 and272 may not be located at the outer regions of the second electrodeassembly 120B. More specifically, as illustrated in FIG. 3A, the firstmulti-tabs 261 and 271 may be located only at roughly lower regions ofthe first winding center 125A in the first electrode assembly 120A(i.e., regions located adjacent to the mutual boundary region 190), andthe second multi-tabs 262 and 272 may be located only at roughly upperregions of the second winding center 125B in the second electrodeassembly 120B (i.e., regions located adjacent to the mutual boundaryregion 190). Therefore, the maximum distance between the first andsecond multi-tabs 261/262 or 271/272 may be equal to or slightly greaterthan the minimum distance between the first and second electrodeassemblies 120A and 120B.

In addition, as illustrated in FIG. 3B, the first and second electrodeassemblies 120A and 120B may include the first and second multi-tabs 261and 262 extended and bent from the inner regions so as to be symmetricalwith each other with respect to the mutual boundary region 190 betweenfirst and second electrode assemblies 120A and 120B or the electrodeterminal 140. The first and second multi-tabs 261 and 262 may beextended and bent, for example, but not limited to, from the innerregions of the first and second electrode assemblies 120A and 120B tothe electrode terminal 140 so as to be symmetrical with each other,respectively. In other words, the first and second multi-tabs 261 and262 may be extended and bent to the electrode terminal 140 from regionscloser to the mutual boundary region 190 of the first and secondelectrode assemblies 120A and 120B than to the first long side portion111 or the second long side portion 112 of the case 110.

Still in other words, the first and second multi-tabs 261 and 262 mayinclude first regions 261 a and 262 a extended from the inner regions ofthe first and second electrode assemblies 120A and 120B, second regions261 b and 262 b extended from the first regions 261 a and 262 a to beadjacent to the case 110, and third regions 261 c and 262 c bent fromthe second regions 261 b and 262 b to be electrically connected to theelectrode terminal 140, respectively.

Here, as the first regions 261 a and 262 a get closer from the case 110to the mutual boundary region 190 of the first and second electrodeassemblies 120A and 120B, bending angles of the first regions 261 a and262 a are more increased. In addition, the second regions 261 b and 262b may be substantially parallel with a longitudinal direction of thecase 110. In addition, the third regions 261 c and 262 c may beconnected to the electrode terminal 140 while being bent roughly atright angle from the second regions 261 b and 262 b.

In addition, since the insulation plate 180 is further located betweenthe first and second electrode assemblies 120A and 120B and the firstand second multi-tabs 261 and 262, and the electrode terminal 140,electrical short circuits may not occur between the case 110, the capplate 130 and/or the predetermined regions of the first and secondelectrode assemblies 120A and 120B, which have polarities opposite tothe first and second multi-tabs 261 and 262. In particular, theinsulation plate 180 is placed roughly on the first regions 261 a and262 a of the first and second multi-tabs 261 and 262.

As described above, according to the embodiment of the presentinvention, the first and second multi-tabs 261 and 262 are extended andbent from the inner regions of the first and second electrode assemblies120A and 120B to the electrode terminal 140 so as to be symmetrical witheach other with respect to the electrode terminal 140 or the mutualboundary region 190 of the first and second electrode assemblies 120Aand 120B, thereby suppressing electrical short circuits between theregions (e.g., the case, the cap plate and/or the predetermined regionsof the first and second electrode assemblies) having polarities oppositeto the first and second multi-tabs 261 and 262.

Referring to FIGS. 4A and 4B, a plan view and a partiallycross-sectional view of first and second electrode assemblies in asecondary battery according to another embodiment of the presentinvention are illustrated.

As illustrated in FIGS. 4A and 4B, the first and second electrodeassemblies 120A and 120B may include first and second multi-tabs (orouter multi-tabs) 361 and 362 located at their outer regions and firstand second multi-tabs (or inner multi-tabs) 371 and 372 located at theirinner regions.

For example, in FIGS. 4A and 4B, the first and second multi-tabs 361 and362 located roughly in the left sides of the first and second electrodeassemblies 120A and 120B may be symmetrical with outer regions (i.e.,regions each adjacent to a first long side portion or a second long sideportion) of the first and second electrode assemblies 120A and 120B, andthe first and second multi-tabs 371 and 372 located roughly in the rightsides of the first and second electrode assemblies 120A and 120B may besymmetrical with inner regions (i.e., regions each adjacent to theboundary region) of the first and second electrode assemblies 120A and120B. Here, the left-side first and second multi-tabs 361 and 362 may bepositive electrode tabs, and the right-side first and second multi-tabs371 and 372 may be negative electrode tabs.

In more detail, in the first electrode assembly 120A, the left-sidefirst multi-tab 361 (positive electrode) may be located at the outerregion of the first electrode assembly 120A, and the right-side firstmulti-tab 371 (negative electrode) may be located at the inner region ofthe first electrode assembly 120A. In the second electrode assembly120B, the left-side first multi-tab 362 (positive electrode) may belocated at the outer region of the second electrode assembly 120B, andthe right-side first multi-tab 372 (negative electrode) may be locatedat the inner region of the second electrode assembly 120B.

Still in other words, the first and second multi-tabs 361 and 362 of thefirst and second electrode assemblies 120A and 120B may be symmetricalwith each other, and the left-side first multi-tab 361 (positiveelectrode) and the right-side first multi-tab 371 (negative electrode)of the first electrode assembly 120A are extended and bent to besymmetrical with each other to then be coupled to the first and secondelectrode terminals 140 and 150, respectively. In addition, the firstand second multi-tabs 371 and 372 of the first and second electrodeassemblies 120A and 120B may be symmetrical with each other, and theleft-side second multi-tab 362 (positive electrode) and the right-sidesecond multi-tab 372 (negative electrode) of the second electrodeassembly 120B are extended and bent to be symmetrical with each other tothen be coupled to the first and second electrode terminals 140 and 150,respectively.

Therefore, the first electrode assembly 120A is coupled to the first andsecond electrode terminals 140 and 150, respectively, in a state inwhich the positive electrode first multi-tab 361 and the negativeelectrode first multi-tab 371 are symmetrical with each other, and thesecond electrode assembly 120B is coupled to the first and secondelectrode terminals 140 and 150, respectively, in a state in which thepositive electrode second multi-tab 362 and the negative electrodesecond multi-tab 372 are symmetrical with each other, thereby improvingcoupling strength, coupling stiffness and coupling reliability betweenthe first and second electrode assemblies 120A and 120B and the firstand second electrode terminals 140 and 150.

Referring to FIGS. 5A and 5B, enlarged cross-sectional viewsillustrating states before and after bending multi-tabs according to anembodiment of the present invention are illustrated. Here, FIG. 5A showsa state before bending the multi-tabs 161 of the electrode assembly120A. As illustrated in FIG. 5A, the multi-tabs 161 are directlyextended in forms of straight lines. In addition, FIG. 5B shows a stateafter bending the multi-tabs 161 of the electrode assembly 120A byconnecting the multi-tabs 161 of the electrode assembly 120A to theelectrode terminal 140. As illustrated in FIG. 5B, the multi-tabs 161are bent in a roughly L-shaped configuration.

As illustrated in FIGS. 5A and 5B and described above, the electrodeassembly 120A may include the first electrode plate 121, the separator122 and the second electrode plate 123.

Here, the first electrode plate 121 may have, for example, but notlimited to, a positive polarity, and may include a first currentcollector plate 121 a having a substantially planar first surface 121 dand a substantially planar second surface 121 e opposite to the firstsurface 121 d. In addition, the first electrode plate 121 may have afirst electrically active material layer 121 b coated on the firstsurface 121 d and/or the second surface 121 e of the first currentcollector plate 121 a.

The multi-tabs 161 may have, for example, but not limited to, astructure in which the first current collector plate 121 a or thenon-coating portion 121 c (see FIG. 1C) is upwardly extended to anexterior side of the first electrically active material layer 121 b ofthe first electrode plate 121. Therefore, the multi-tab 161 may alsohave a substantially planar first surface 161 d and a substantiallyplanar second surface 161 e opposite to the first surface 161 d. Inaddition, the first surface 121 d of the first current collector plate121 a and the first surface 161 d of the multi-tab 161 may besubstantially coplanar, and the second surface 121 e of the firstcurrent collector plate 121 a and the second surface 161 e of themulti-tab 161 may also be substantially coplanar. In addition, the firstcurrent collector plate 121 a and the multi-tabs 161 may havesubstantially the same thickness. Of course, in addition to thestructure stated above, the multi-tabs 161 may also be provided byattaching a separate member to the first current collector plate 121 aor the non-coating portion 121 c outwardly extended from the firstelectrically active material layer 121 b.

The separator 122 is positioned between the first electrode plate 121and the second electrode plate 123. A length (or height) of theseparator 122 may be greater than a length (or height) of the firstelectrode plate 121 and/or the second electrode plate 123. That is tosay, a top end of the separator 122 may be positioned higher than topends of the first electrode plate 121 and/or the second electrode plate123.

The second electrode plate 123 may have, for example, but not limitedto, a negative polarity. The second electrode plate 123 is located atone side of the separator 122 and may include a second current collectorplate 123 a having a substantially planar first surface 123 d and asubstantially planar second surface 123 e opposite to the first surface123 d, and a second electrically active material layer 123 b coated onthe first surface 123 d and/or the second surface 123 e of the secondcurrent collector plate 123 a. In addition, a safety function layer(SFL) 123 f allowing lithium ions to pass while blocking migrationelectrons may be further located on a surface of the second electricallyactive material layer 123 b. The SFL 123 f may be made of, for example,but not limited to, an inorganic material, such as ceramic, and maysuppress decomposition of electrolyte by blocking the electronmigration.

Here, the length (or height) of the second electrode plate 123 may begreater than that of the first electrode plate 121. Thus, excessivelithium ions or metallic ions may not exist inside of the electrodeassembly 120A (particularly, on the surface of the second electricallyactive material layer). In addition, the length (or height) of theseparator 122 is largest, and the length (or height) of the firstelectrode plate 121, exclusive of the multi-tab 161, is smallest.

In addition, since the separator 122 is positioned between the multi-tab161 and the second electrode plate 123, the multi-tab 161 can beprevented from being directly electrically short-circuited to the secondelectrode plate 123 (e.g., the second current collector plate 123 a orthe second electrically active material layer 123 b) even if themulti-tab 161 is bent to be connected to the electrode terminal 140.

In addition, in order to more efficiently suppress the multi-tab shortcircuit in the embodiment of the present invention, an insulating layer280 may be coated on surfaces of the multi-tabs 161. That is to say, theinsulating layer 280 may be coated on the first surface 161 d and/or thesecond surface 161 e of the multi-tab 161. The insulating layer 280 maybe coated on the first surface 161 d and/or the second surface 161 ewhile being in contact with the first electrically active material layer121 b. Moreover, a topmost height of the insulating layer 280 may beequal to, for example, a topmost height of each of the separators 122.If the topmost height of the insulating layer 280 is smaller than thatof the separator 122, the multi-tabs 161 may be at risk of being broughtinto direct contact with the second electrode plate 123 (e.g., thesecond current collector plate 123 a, the second electrically activematerial layer 123 b, etc.) when they are bent. In addition, if thetopmost height of the insulating layer 280 is larger than that of theseparator 122, the insulation level of the multi-tab 161 is increased,but the insulating efficiency between the multi-tabs 161 and the secondelectrode plate 123 may not be improved any more.

A thickness of the insulating layer 280 may be smaller than a thicknessof the first electrically active material layer 121 b. The thickness ofthe first electrically active material layer 121 b may be in the rangefrom, for example, but not limited to, about 100 μm to about 600 μm, andthe thickness of the insulating layer 280 may be in the range from about0.1 μm to about 100 μm, preferably from about 1 μm to about 50 μm, morepreferably from about 3 μm to about 8 μm. If the thickness of theinsulating layer 280 is larger than that of the first electricallyactive material layer 121 b, the overall thickness of the electrodeassembly 120A may be increased as much as the thickness of theinsulating layer 280, and the multi-tabs 161 may not be properly bent.Moreover, when the multi-tabs 161 are bent, the insulating layer 280 maybe extracted from the multi-tabs 161.

As described above, a double insulating structure including theinsulating layer 280 and the separator 122 may be positioned between themulti-tabs 161 and the second electrode plate 123, thereby preventingelectrical short circuits between the multi-tabs 161 and the secondelectrode plate 123, that is, increasing the insulation level of themulti-tabs 161.

Moreover, a triple insulating structure including the insulating layer280, the separator 122 and the SFL 123 f may be positioned between themulti-tabs 161 and the second electrode plate 123, thereby moreefficiently preventing electrical short circuits between the multi-tabs161 and the second electrode plate 123. That is to say, the insulationlevel of the multi-tabs 161 may be further increased.

The insulating layer 280 may be made of, for example, but not limitedto, an organic material, an inorganic material, or an organic-inorganiccomposite (or hybrid) material, using one or a combination of processesselected from the group consisting of an inkjet printing process, acoating process, a dip coating process, a doctor blade process, a drydipping process, a hydro thermal reaction, a sol-gel process, a sprayingprocess, aerosol deposition, chemical vapor deposition, physical vapordeposition, a roll to roll process, a casting process, ion beamdeposition, and equivalents thereof.

In addition, the organic material (or binder) may include, for example,but not limited to, one or a mixture of materials selected from thegroup consisting of polyimide (PI), polyamideimide (PAI), polyvinylidenefluoride (PVdF), polyurethane (PU), polyurea, polycarbonate (PC),polyethylene terephthalate (PET) polymethyl methacrylate (PMMA),polybutylene terephthalate (PBT), polyvinyl alcohol (PVA), polyvinylbutyral (PVB) and equivalents thereof.

In addition, the inorganic may include, for example, but not limited to,one or a mixture of two materials selected from the group consisting ofalpha alumina (α-Al2O3), alumina (Al2O3), aluminum hydroxide (Al(OH)3,bohemite), lead zirconate titanate (Pb(Zr,Ti)O3(PZT)), titanium dioxide(TiO₂), zirconia (ZrO₂), yttria (Y₂O₃), yttria stabilized zirconia(YSZ), dysprocia (Dy₂O₃), gadolinia (Gd₂O₃), ceria (CeO₂), gadoliniadoped ceria (GDC), magnesia (MgO), barium titanate (BaTiO₃), nickelmanganite (NiMn₂O₄), potassium sodium niobate (KNaNbO₃), bismuthpotassium titanate (BiKTiO₃), bismuth sodium titanate (BiNaTiO₃),bismuth ferrite (BiFeO₃), bismuth zinc niobate (Bi₁₋₅Zn₁Nb_(1.5)O₇),tungsten oxide (WO), tin oxide (SnO2), lanthanum-strontium-manganeseoxide (LSMO), lanthanum-strontium-iron-cobalt oxide (LSFC), aluminumnitride (AlN), silicon nitride (SiN), silicon oxide (SiO2), zinc oxide(ZnO), hafnia (HfO2), titanium nitride (TiN), silicon carbide (SiC),titanium carbide (TiC), tungsten carbide (WC), magnesium boride (MgB),titanium boride (TiB), calcium oxide (CaO), cobalt ferrite (CoFe2O4),nickel ferrite (NiFe2O4), barium ferrite (BaFe2O4), nickel zinc ferrite(NiZnFe2O4), zinc ferrite (ZnFe2O4), manganese cobalt spinel oxideMnxCo3-xO4 (where x is a positive real number 3 or less), a mixture ofmetal oxide and metal nitride, a mixture of metal oxide and metalcarbide, a mixture of ceramic and polymer, a mixture of ceramic andmetal, and equivalents thereof.

In addition, the average particle diameter of the inorganic material maybe in the range from, for example, but not limited to, about 0.1 μm toabout 100 μm, preferably from about 0.3 μm to about 10 μm, morepreferably from about 0.5 μm to about 5 μm.

Meanwhile, in order to allow the multi-tabs 161 to be electricallyconnected to the electrode terminal 140, the multi-tabs 161 are bent ina roughly L-shaped configuration. Or after the multi-tabs 161 areconnected to the electrode terminal 140, the multi-tabs 161 are bent ina roughly L-shaped configuration. Here, since the multi-tabs 161 arebent while being in close contact with each other, not only themulti-tabs 161 but also the separator 122 and/or the second electrodeplate 123 are bent at a predetermined angle. In particular, theseparators 122 are bent with the multi-tabs 161, as illustrated in FIG.5B. Here, since the insulating layer 280 is coated on the surfaces ofthe multi-tabs 161, as described above, the insulating layer 280 is alsobent.

Therefore, the multi-tabs 161 and the insulating layer 280 are broughtinto contact with/close contact with the separator 122 while being bent.Although FIG. 5B shows that the multi-tabs 161, the separator 122 andthe second electrode plate 123 are spaced apart from one another, theymay be substantially closely adhered to/brought into close contact withone another. Here, the electrical short circuits can be prevented fromoccurring between the multi-tabs 161 and the and the second electrodeplate 123 (i.e., the second current collector plate 123 a and/or thesecond electrically active material layer 123 b) by the doubleinsulating structure including the insulating layer 280 and theseparator 122, or the triple insulating structure including theinsulating layer 280, the separator 122 and the SFL 123 f, positionedbetween the multi-tab 161 and the second electrode plate 123.

In order to more improve the insulation efficiency, the insulating layer280 that is the same as described above may also be located on thesurface of the second current collector plate 123 a exposed through thesecond electrically active material layer 123 b. Therefore, the tripleinsulating structure including the insulating layer 280, the separator122 and the insulating layer 280 may be provided between the multi-tabs161 and the second current collector plate 123 a, thereby improving theinsulating efficiency between the multi-tabs 161 and the second currentcollector plate 123 a.

Meanwhile, the mutual relationships, materials, types and configurationsof the insulating layer 280, the first electrode plate 121, theseparators 122 and the second electrode plate 123 located on themulti-tabs 161 can be commonly applied to all embodiments of the presentinvention.

Referring to FIGS. 6A and 6B, enlarged cross-sectional viewsillustrating states before and after bending multi-tabs according toanother embodiment of the present invention are illustrated.

As illustrated in FIGS. 6A and 6B, an insulating layer 380 formed onsurfaces of the multi-tabs 161 may be spaced apart a predetermineddistance apart from the first electrically active material layer 121 b.That is to say, the insulating layer 380 may not be necessarily broughtinto direct contact with the first electrically active material layer121 b but may be located only on areas needed to be insulated.

In more detail, the insulating layer 380 may be located only atpredetermined areas of the multi-tabs 161 facing (corresponding to) atop end of the second electrode plate 123 spaced apart from the firstelectrically active material layer 121 b. That is to say, the insulatinglayer 380 may be located only at predetermined areas of the multi-tabs161, where the multi-tabs 161 are not electrically short-circuited tothe second electrode plate 123 even if the separator 122 is pierced bybent regions of the multi-tabs 161 at the time of bending the multi-tabs161.

The insulating layer 380 may be spaced, for example, but not limited to,about 0.1 mm to about 3 mm from the first electrically active materiallayer 121 b.

As described above, since the insulating layer 380 is located only atthe predetermined areas of the multi-tabs 161 spaced apart from thefirst electrically active material layer 121 b, the manufacturingprocess of the multi-tabs 161 can be facilitated. That is to say, theinsulating layer 380 is located on a non-coating portion of an electrodeplate, followed by performing a notching process using a laser beam or amold, thereby providing the multi-tabs 161. As described above, sincethe insulating layer 380 is located only at the predetermined areas ofthe multi-tabs 161, electrical/mechanical loads during the notchingprocess using a laser beam or a mold can be reduced, therebyfacilitating the manufacturing process.

Referring to FIGS. 7A and 7B, enlarged cross-sectional views ofmulti-tabs according to another embodiment of the present invention areillustrated.

As illustrated in FIG. 7A, each of the multi-tabs 161 may have asubstantially planar first surface 161 d, a substantially planar secondsurface 161 e opposite to the first surface 161 d, a third surface 161 fconnecting first ends of the first and second surfaces 161 d and 161 e,and a fourth surface 161 g connecting second ends of the first andsecond surfaces 161 d and 161 e and opposite to the third surface 161 f.The insulating layer 280 may be located only on the first and secondsurfaces 161 d and 161 e, which are relatively wide surfaces. That is tosay, the third and fourth surfaces 161 f and 161 g of the multi-tab 161may be exposed.

In other words, the insulating layer 280 is located on first and secondsurfaces of the non-coating portion, and the multi-tabs 161 are thenformed by performing the notching (or cutting) process using a laserbeam or a mold. Therefore, as described above, the insulating layer 280may not be located on the third and fourth surfaces 161 f and 161 g ofthe multi-tab 161 but may be exposed. That is to say, one surface of theinsulating layer 280 may be coplanar with the third surface 161 f of themulti-tab 161, and the other surface of the insulating layer 280 may becoplanar with the fourth surface 161 g of the multi-tab 161.

Meanwhile, as illustrated in FIG. 7B, the insulating layer 280 may belocated not only on the first and second surfaces 161 d and 161 e, whichare relatively wide surfaces, but also on the third and fourth surfaces161 f and 161 g, which are relatively narrow surfaces. That is to say,none of the first, second, third and fourth surfaces 161 d, 161 e, 161 fand 161 g of the multi-tab 161 may be exposed through the insulatinglayer 280.

In other words, the insulating layer 280 is located on the first andsecond surfaces of the non-coating portion, and the multi-tabs 161 arethen formed by performing the notching (or cutting) process using alaser beam or a mold. Therefore, as described above, the insulatinglayer 280 may be located not only on the first and second surfaces 161 dand 161 e but also on the third and fourth surfaces 161 f and 161 g ofthe multi-tab 161. That is to say, during the notching process using amold, a portion of the insulating layer 280 located on the first surface161 d or the second surface 161 e is pushed to the third and fourthsurfaces 161 f and 161 g, so that the third and fourth surfaces 161 fand 161 g of the multi-tab 161 are covered by the insulating layer 280.The insulating layer 280 located on the third and fourth surfaces 161 fand 161 g of the multi-tab 161 can also prevent electrical shortcircuits from occurring between the third and fourth surfaces 161 f and161 g and the second electrode plate 123 through the above-describedprocess.

Although the foregoing description has been made with regard to a casewhere the insulating layer 280 is located on the surfaces of themulti-tabs 161, it should be understood by one skilled in the art thatthe insulating layer 280 is located on the surfaces of the first andsecond multi-tabs 161/171 and/or 162/172. Moreover, it should beunderstood by one skilled in the art that these features can be commonlyapplied to all embodiments of the present invention.

Referring to FIGS. 8A to 8C, schematic views illustrating amanufacturing method of a secondary battery according to an embodimentof the present invention.

As illustrated in FIG. 8A, the first electrode first multi-tab 161 andthe second electrode first multi-tab 171 of the first electrode assembly120A are welded to the first electrode terminal 140, that is, the firstcurrent collector plate 144, and the second electrode terminal 150, thatis, the second current collector plate 154, provided in the cap plate130, and the first electrode second multi-tab 162 and the secondelectrode second multi-tab 172 of the second electrode assembly 120B arealso welded to the first electrode terminal 140 and the second electrodeterminal 150, respectively. Here, the first electrode first multi-tab161 and the second electrode first multi-tab 171 of the first electrodeassembly 120A, and the first electrode second multi-tab 162 and thesecond electrode second multi-tab 172 of the second electrode assembly120B, have yet to be bent. In addition, if the welding process iscompleted, the insulation plate 180 is placed on the cap plate 130. Thatis to say, the insulation plate 180 is placed on the first electrodefirst multi-tab 161 and the first electrode second multi-tab 162, whichare positioned on the first current collector plate 144, and the secondelectrode first multi-tab 171 and second electrode second multi-tab 172,which are positioned on the second current collector plate 154.

As illustrated in FIG. 8B, the first and second electrode assemblies120A and 120B are bent roughly at right angle from the cap plate 130.Accordingly, the first and second multi-tabs 161 and 162 provided in thefirst and second electrode assemblies 120A and 120B are bent with thefirst regions 161 a and 162 a, the second regions 161 b and 162 b andthe third regions 161 c and 162 c. In addition, as the result of thebending process, the insulation plate 180 may be substantially coveredby the first and second electrode assemblies 120A and 120B, the firstand second multi-tabs 161 and 162 and the cap plate 130. In addition, asthe result of the bending process, the first and second electrodeassemblies 120A and 120B are brought into close contact with each otherto be parallel with each other.

As illustrated in FIG. 8C, the first and second electrode assemblies120A and 120B being in close contact with each other are inserted intothe case 110. That is to say, until the cap plate 130 closes the case110, the first and second electrode assemblies 120A and 120B and the capplate 130 are pushed into the case 110.

Next, the cap plate 130 is welded to the case 110 to then be fixed, andan electrolytic solution is inserted into the case 110 through anelectrolyte injection hole. However, this process may be omitted in acase of a solid battery requiring no electrolytic solution.

Here, as described above, according to various embodiments of thepresent invention, since the first and second multi-tabs 161 and 162 arelocated only at outer regions (or inner regions) of the first and secondelectrode assemblies 120A and 120B, as the result of the bendingprocess, the first and second multi-tabs 161 and 162 are bent so as tobe symmetrical with each other. Therefore, it is possible to preventelectrical short circuits between the first and second multi-tabs 161and 162, and the case, the cap plate and/or the first and secondelectrode assemblies 120A and 120B, which have polarities opposite tothe first and second multi-tabs 161 and 162, from occurring during orafter the manufacture of the secondary battery 100.

Referring to FIG. 9, a perspective view illustrating an example of abattery module using a secondary battery 100 according to an embodimentof the present invention is illustrated.

As illustrated in FIG. 9, multiple secondary batteries 100 are arrangedin a line and multiple bus bars 510 are coupled to the multiplesecondary batteries 100, thereby completing the battery module 1000. Forexample, a first electrode terminal 140 of one of the multiple secondarybatteries 100 and a second electrode terminal 150 of another adjacentsecondary battery 100 may be welded to each other using the bus bar 510,thereby providing the battery module 1000 including the multiplesecondary batteries 100 connected to one another in series. The bus bar510 may be made of aluminum or an aluminum alloy, and a first terminalplate 131 of the first electrode terminal 140 and a second terminalplate 141 of the second electrode terminal 150 may also be made ofaluminum or an aluminum alloy, thereby allowing the bus bar 510 to beeasily welded to the first electrode terminal 140 and the secondelectrode terminal 150.

Although the foregoing embodiments have been described to practice thesecondary battery of the present invention, these embodiments are setforth for illustrative purposes and do not serve to limit the invention.Those skilled in the art will readily appreciate that many modificationsand variations can be made, without departing from the spirit and scopeof the invention as defined in the appended claims, and suchmodifications and variations are encompassed within the scope and spiritof the present invention.

1. A secondary battery comprising: a case; a first electrode assemblyhoused inside of the case and having a first multi-tab; a secondelectrode assembly housed inside of the case side by side with the firstelectrode assembly and having a second multi-tab; and a cap plateclosing the case and having electrode terminals electrically connectedto the first and second multi-tabs of the first and second electrodeassemblies, wherein the first and second multi-tabs are formed to besymmetrical to each other with respect to a mutual boundary region ofthe first and second electrode assemblies, and an insulating layer iscoated on the surfaces of the first and second multi-tabs.
 2. Thesecondary battery of claim 1, wherein the first and second multi-tabsare located only at regions closer to the case than to the mutualboundary region of the first and second electrode assemblies,respectively.
 3. The secondary battery of claim 1, wherein the first andsecond multi-tabs are extended to the electrode terminals from regionscloser to the case than to the mutual boundary region of the first andsecond electrode assemblies, respectively.
 4. The secondary battery ofclaim 1, wherein the first electrode assembly includes a first windingcenter, the second electrode assembly includes a second winding center,the case includes a first long side portion closely contacting the firstelectrode assembly, a second long side portion closely contacting thesecond electrode assembly, the first multi-tab is positioned between thefirst winding center and the first long side portion, and the secondmulti-tab is positioned between the second winding center and the secondlong side portion.
 5. The secondary battery of claim 1, wherein thefirst and second multi-tabs are located only at regions closer to themutual boundary region than to the case.
 6. The secondary battery ofclaim 1, wherein the first and second multi-tabs are extended to theelectrode terminals from regions closer to the mutual boundary regionthan to the case.
 7. The secondary battery of claim 3, wherein the firstand second multi-tabs include first regions extended from the first andsecond electrode assemblies, second regions extended from the firstregions and located adjacent to the case, and third regions bent fromthe second regions and connected to the electrode terminals,respectively.
 8. The secondary battery of claim 1, wherein the firstelectrode assembly includes a first winding center, the second electrodeassembly includes a second winding center, the first multi-tab ispositioned between the first winding center and the mutual boundaryregion, and the second multi-tab is positioned between the secondwinding center and the mutual boundary region.
 9. The secondary batteryof claim 1, wherein the first and second multi-tabs include outermulti-tabs located in regions closer to the case than to the mutualboundary region, and inner multi-tabs located in regions closer to themutual boundary region than to the case, respectively.
 10. The secondarybattery of claim 1, wherein the insulating layer includes an insulatingorganic material.
 11. The secondary battery of claim 1, wherein theinsulating layer includes an insulating inorganic material.
 12. Thesecondary battery of claim 1, wherein the insulating layer includes aninorganic filler and an organic binder.
 13. The secondary battery ofclaim 1, wherein, each of the first and second electrode assembliescomprises: a first electrode plate including a first current collectorplate and a first electrically active material layer coated on the firstcurrent collector plate; a separator positioned at one side of the firstelectrode plate; and a second electrode plate include a second currentcollector plate and a second electrically active material layer coatedon the second current collector plate, wherein the first multi-tab isformed such that the first current collector plate is extended to theoutside of the first electrically active material layer of the firstelectrode plate of the first electrode assembly, and the secondmulti-tab is formed such that the second current collector plate isextended to the outside of the second electrically active material layerof the second electrode plate of the second electrode assembly.
 14. Thesecondary battery of claim 13, wherein the insulating layer and theseparator are positioned between each of the first and second multi-tabsand the second electrode plate.
 15. The secondary battery of claim 13,further comprising a safety function layer (SFL) located on the secondelectrically active material layer, wherein the insulating layer, theseparator and the SFL are positioned between each of the first andsecond multi-tabs and the second electrode plate.
 16. The secondarybattery of claim 6, wherein the first and second multi-tabs includefirst regions extended from the first and second electrode assemblies,second regions extended from the first regions and located adjacent tothe case, and third regions bent from the second regions and connectedto the electrode terminals, respectively.